Telephone-exchange system.



`B. G. DUNHAM.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY 22, 1916.

Patented Nov. 21, 1916.

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B. G. DUNHAM.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED'MAY 22, 1916.

Patented Nov. 21, 1916.

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l UNTTED STATES PATENT GFFTQE.

BERT G. DUNHAM, OF HAWTHORNE, NEW' JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, 0F NEVI YORK, N. Y., A CORPORATION OF NE/V YORK.

TELEPHONE-EXCHANGE SYSTEM.

specification of Letters Patent.

Patented N ov. 21, 1916.

Application filed May 22, 1916. Serial No. 99,130.

To 1J/Z Iwhom itA may concern:

Be it known that I, BERT G. DUNHAM, a citizen of the United States, residing at Hawthorne, in the county of Passaic and State of New Jersey, have invented certain new and useful improvements in Telephone Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems employing party'line working. in such systems it frequently happens that a subscriber at one of the substations desires a connection with a subscriber at another substation of the same line. The ordinary busy test will in this case give a false busy indication because a test guard is placed upon the multiple called terminal of the line when thev answering end of the connecting circuit connects with such line, and not because such line is already busy by reason of a conversation being held with some other subscriber. It is not desirable, however, that either the calling subscriber or the operator be required to know from the mere number of the called station whether it is on the same line as the calling station or not.

One of the features of this invention is an improved means for giving a special audible signal to the operator in all cases of such revertive calls, and the novelty kconsists in a circuit arrangement wherein a discriminating relay associated with the connecting circuit is energized when the operator depresses her listening key, this relay, in operating, preparing aV circuit including a winding of the operators head set. When the test contact of the calling end of the connecting circuit is placed in engagement with the test contact of the desired line, if such test terminal is a mutliple of the calling test terminal, this discriminating relay will become denergized, due to a shunt therearound including the multiple calling and called test terminals, and at its back contact will connect an interrupted source of current in circ-uit with said winding. Thus, as long as the test contact of the calling end of the connecting circuit is maintained in engagement with the contact of the line being tested, a buzz will be produced in the operators head set and thus indicate to her that the call is revertiva If the terminal of the line tested belongs to a busy non-party line, a relay in the sleeve conductor is energized when the test contact of the calling end of the connecting circuit is placed in engagement with the test terminal, and closes a circuit including the armature and front contact of said discriminating relay and said winding.

Another feature of the invention is a simplified starter wire circuit for associating idle automatic line nders with calling lines, and the novelty consists in an arrangement whereby, upon the initiation of a call in a line of a given group, the starter wire is grounded and is closed to the succeeding idle finder, as well as to the inder of the group with which it is normally associated, and if the finder of the latter group is idle, a relay is operated to open the connection of the starting ground with such succeeding nder, but not otherwise.

The invention will be more readily understood when described with reference to the accompanying drawings, wherein- Figure'l indicates a calling line and the answering end of a connecting circuit, and Fig. 2 a called line and the calling end of a connecting circuit.

Upon the removal of the receiver at substation A, the line relay 100 is energized over the line circuit. This relay, in attracting its left armature, grounds the multiple 101 of the calling line, and, in attracting its right armature,' energizes relays 102,V 103, common to the group of lines containing substation A. Relay 102, in attracting its right armature, grounds commutator multiple segment 10a of the group to which substation A belongs to render the group calling. Relay 103, in attracting its right armature, clcses the following circuit to energize the escape magnet 106 of the line finder side switch: free pole of battery, primary stepping magnet 105, escape magnet 106, side-switch arm 1, armature and back contact of magnet 105, armature and back contact of magnet 107, conductor 108, right armature and front contact of relay 103, conductor 109, conductor 200, outer armature and back contact of relay 201, conductor 202, to ground at the armature and back contact of the calling supervisory relay 203. Magnet 105 does not energize in this circuit. The escape magnet 106 is constructed to release the side switch from position to position, upon its energization.

In position 2, arm 1 connects magnet 105 over the back contacts of magnets`105, 107, to grounded conductor 108, whereupon the iinder brush shaft 119 is given a primary movement by the operation of such magnet 105. In position 2, arm 2 closes the following circuit for relay 116: free pole of battery, magnet 107, arm 2, left winding of relay 116, armature and back contact of magnet 107 to grounded conductor 108. This relay is adapted to attract its armature upon the closure of this circuit, but magnet 107 remains inert. Relay 116, at its inner armature and front Contact, connects the escape magnet over arm 3 and its second contact to the commutator brush 115. When brush 115 encounters the calling comniutator segment 101, now grounded, escape magnet 106 energizes over the following circuit, and releases the side switch into position 3: free pole of battery, magnets 105, 106, conductors 117, 118, armature and front contact of relay 116, arm 3 and its second contact, conductors 120, 130, commutator brush 115, segment 104, now grounded at the armature and front contact of relay 102. Arm 1, in moving out of position 2, opens the circuit of magnet 105, thus stopping the primary movement of the finder brush shaft 119 withV a set of brushes 110, 111, 112 in operative relation to multiples of the calling line group containing those of the calling line 101, 113 and 114.

In position 3, relay 116 is energized over the following circuit: free pole of battery, magnets 105, 106, arm 2 and its third contact, left winding of relay 116, armature and back contact of magnet 107, grounded conductor 108. Magnets 105 and 106 do not energize in this circuit. Relay 116, at its outer armature and front contact, closes the following circuit to operate the secondary stepping magnet 107 to drive the brushes 110, 111 and 112 over the multiples containing those of the calling line 101, 113 and 114: free pole of battery, magnet 107, outer armature and front Contact of relay 116, arm 1 and its third contact, armature and back contact of magnet 105, armature and back contact of magnet 107, to grounded conductor 108. The magnet 107 interrupts the circuit traced through the left winding of relay 116, as well as its own circuit, and this relay therefore vibrates, lexcept when the brush 112 engages the test multiples 114 of busy lines, when it is held energized from battery on such termina-ls, brush 112, conductor 120, arm 3 and its third Contact, right winding of relay 116, to ground, as will be more particularly described hereinafter. When, however, the brush 112 reaches the calling line multiple 114, relay 116 becomes f denergized, and, since ground is present on multiple 101 of the calling line, the following circuit is closed for escape magnet 106: free pole of battery, magnets 105, 106, conductors 117, 118, inner armature and back contact of relay 116, arm 5 and its third contact, brush 110, terminal 101 to ground at the left armature and front contact of relay 100. Magnet 106, upon its energization, releases the side switch into position 4. Thus, the finder brushes 110, 111, 112 remain on the calling line multiples 101, 113, 114. In position t, the calling line is extended by arms 1 and 5 to the conductors 121, 122, whereupon the calling supervisory relay 203 is energized over the calling line circuit.

In position f1, arm 3 of the finder side switch closes the following circuit to energize the cut-off relay 128 of the calling line: free pole of battery, `resistance 206, conductors 211, 125, arm 3 and its fourth contact, conductor 120, brush 112, terminal 114, cutoff relay 128, to ground. This potential applied to multiples 11e by brush 112, holds relay 116 of a moving linder energized by its right winding as the brush 112 of such finder wipes over such multiples, as hereinbefore described. Relay 128, in attracting its armatures, denergizes the line relay 100, which, in retracting its left armature, removes the calling condition :from the multiples 101 of the calling line, and in retracting its right armature, denergizes group lrelays 102, 103. Relay 102, in retracting its right armature, removes the calling condition from the commutator multiples 101 ofthis group. Y

Relay 203, in attracting its armature, operates a relay 204:, which lights the calling lamp 2:10, whereupon the operator depresses her listening key 239, which connects her head-set 238 in circuit with the calling line, assuming' plug 270 and 271 to be inserted in jacks 272, 273 respectively. The actuation of the listening key 239 closes the following circuit for a relay 205: free polerof battery, resistance 206, contact 297 of listening key 239, conductor 208, relays 205, 209, to ground. Relay 209 marginal and does not operate in this circuit. Relay 205, by attracting' its armature, closes one break in the circuit of winding 210 of the operators headset. The operator now asks the calling party the number of the line wanted. The talking circuit between the operator and the calling party will not be traced in detail since it is readily apparent from the drawing. The operator now touches 'the tip of the calling the jack 212 of the wanted line. If such line is a busy non-party line, the sleeve will have potential impressed upon it from battery, through the sleeve relay 213 of another calling plug. If the contacts of jack 212 are multiples of the contacts 101, 113, v114 of the finder, i. e. if the call is -revertive,

plug' 211 to the sleeve of' potential is impressed upon the sleeve of such jack from battery, through resistancey 206, conductors 214 and 125, arm 3 of the finder and its fourth contact, conductor 120, brush 112, terminal 114. Relay 209 is adapted to become energized when the tip of the plug is touched to the sleeve of the jack since a circuit including the inner armature and back contact of relay 213 is closed for it in addition to the path traced through relay 205. In attracting its armature, relay 209 closes the following circuit through the winding 210 of the head set: free pole of battery, resistance 215, armature and front contact of relay 209, conductor 216, armature and front contact of relay 205, conductors 217, 218, winding 210, to earth. Each time the operator touches the tip of the plug 211 to the sleeve of jack 212, a single click will be produced in her receiver, due to the rush of current through winding 210. If, however, the sleeve of jack 212 is a multiple of terminal 114, to which the finder shown in Fig. 1 has just been connected, the moment the operator touches the tip of plug 211 to the sleeve of jack 212 discriminating relay 205 will be short-circuited by reason of the closure of the following shunt path: free pole of battery, resistance 206, conductors 214, 125, arm 3 and its fourth contact, conductor 120, brush 112, terminal 114, Sleeve Contact 212, multipled to terminal 114, tip of plug 211, back contact of relay 213, conductor 220. Relay 205 will thereupon release its armature, and, at its back contact, connect the winding 210 of the head-set to the front contact of relay 209 through a relay 221. This circuit leads through an armature and back contact of relay 221, and thus such relay acts as a buzzer. Consequently, as long as the operator maintains the tip of plug. 2,11 in contact with the sleeve of jack 212, she will hear a buzzing sound in her head-set informing her that the call is revertive, whereupon she will throw a ringing key 222 which may be any of the well-known types of locking keys, and which controls the connection of generators 274, 275 with the line, depending upon the number of the substation desired on the party line, and insert the plug 211 into the jack 212. Upon the insertion of plug 211 in ack 212, sleeve relay 213 is energized in series with the cut-off relay 128. Relay 213, in attracting its armature 251, connects conductor 231 to the tip of the plug, and in attracting its armature 252, energizes relay 201 and lights lamp 233. By attracting its armature 253, relay 213 deenergizes relay. 204, extinguishing the lamp 240. Relay 201, in attracting its armature, closes the following circuit for a relay 226, adapted to apply ringing current to the called line: free pole of battery, armature and front contact of relay 201, relay 226,

conductor 227, armature and back contact of relay 228, and armature and back contact of relay 229 to ground. Relay 5226, in attracting its armatures, connects current from the generator 274 or 275 to the called line. When the called party removes his receiver, relay 229 attracts its armature, thus removing the shunt from about relay 228, which thereupon energizes. Relay 228, in attracting its armature, locks itself to ground and shunts out relay 226, which, in falling back opens the ringing circuit and reconnects conductors 231, 232 to the tip and ring of the calling plug 211. Relay 229, in energizing, also releases the ringing key 222 in the wellknown manner. The called supervisory relay 241 is thereupon energized over the called line, and, in attracting its armature, extinguishes supervisory lamp 233. The parties may now converse.

Upon the termination of the conversation and the replacement of the receiver by the calling party, relay 203 becomes denergized and closes the following circuit for relay 204: ground, armature and back contact of relay 203, conductor 202, outer armature and front contact of relay 201, conductors 290, 291, relay 204, free pole of battery. Relay 204, in operating, lights the supervisory lamp 240. Then the called party hangs up his receiver, relay 241 falls back, closing the circuit of lamp 233. The operator thereupon withdraws plug 211 from jack 212, which results in relay 213 becoming dele'nergized. Relay 213, in retracting its upper armature, denergizes relay 201, which opens the locking` circuit of relay 228 at its inner armature, and at its outer armature closes the release circuit for the finder as follows: armature and back contact of calling supervisory relay 203, conductor 202, outer arma-- ture and back contact of relay 201, conductor 200, conductor 109, right armature and back contact of relay 103, primary off-normal contact 126, release magnet 127, free pole of battery. Magnet 127, in attracting its left armature, locks itself over the olinormal contact 126 to ground. lVhen the finder brush shaft 119 is completely restored, this off-normal contact opens and unlocks the release magnet. The finder in releasing opens the circuit of cut-off relay 128.

Going back to that point in the operation where the removal of the receiver starts a finder seeking the calling line, it will be remembered that the initiation of such call energized group relay 103, which, in attracting its right armature, extended the conductor 109 grounded at the armature and back contact of 'calling supervisory rela-y 203, to the escape magnet 106 to initiate the primary movement of the finder brush shaft. In parallel with magnet 106, a quick acting relay 131 is energized when relay 103 opcrates, this circuit being as follows: free pole of battery, relay 131, spring 132, conductors 133, 117, arm 1 and its first contact, armatures and back contactsfof magnets 105, 107, conductor 103, right armature and front contact of relay 103, conductors 109, 200, outer armature and back contact of relay 201, conductor 202, to ground at the `armature and back contact of the calling supervisory relay 203. Relay 131, by attracting its right armature, locksvitself directly to grounded conductor 103, and by attracting its left armature, opens the connection between the grounded left-hand armature of relay 102 and the out-starter wire 134, leading to the escape magnet 106 of the next finder. If the finder shown in F ig. 1 had been busy, relay 203 would have been energized, and consequently the circuit for relay 131 just traced would ynot have been completed, and this relay failing to energize, the grounded left-hand armature of relay 102 would be connected over the left armature of relay 103 to the out-starter wire 1341, leading to the escape magnet 10G of the next finder, to set the finder shaft in motion seeking the calling line. Thus, the starter wire is normally extended to the next idle finder. Assuming the iinder shown in Fig. 1 to be the next idle finder, the circuit may be continued as follows: in-starter wire 135, left armature and back Contact of relay 102, relay 103, conductor 136, right armature and back contact of magnet 127, resistance 137, free pole of battery. Relay 103, in attracting its left armature, connects the in and out-starter wires 135, 134 together, and in attracting its right armature, energizes the escape magnet 106 of such finder as described, which, upon energizing, releases the side switch into position 2 to initiate the primary movement of the finder brush shaft. From this point on the operations are the sameas those already traced.

lhat is claimed is:

1. In a telephone exchange system, the combination with telephone lines' having multiple calling and called test terminals, a, connecting' circuit, means for associating a calling line with said connecting circuit and changing the electrical condition of its test Aterminal, and an operators telephone set adapted to be associated with said connecting circuit, of a relay associated with said connecting circuit, a circuit adapted to energize the same, a key for closing said circuit, a circuit for operating said relay closed when the desired line is tested, and a shunt about said relay closed during such testing operation if the calling and called test terminals are multiples of the same line, the closure of said shunt denergizing said relay, and means rendered operative by the inert condition thereof for producing a tone in said set.

2. In a telephone exchangel system, the combination with calling and called telephone lines including party lines, a connecting circuit, means for 'associating calling lines with said 4connecting circuit, and an operators telephone set, of a discriminating relay, a keytorinclude said set iny circuit with the calling line and to energize saidrelay to prepare a circuit including said set, a relay energized when the called line is tested to complete said circuit whereby a single click is produced in said set, a source of interrupted current, and a shunt about said discriminating,relay closed when the calling and called lines are the same, to denergize said relay, which in its inerty condition connects said source to said set to produce a tone in said set.

3. In a telephone exchange system, the combination with calling and called telephone lines including party lines, jacks wherein saidlines terminate as called lines, a connecting circuit including a calling plug, means for associating calling lines `with said connecting circuit, and an operators telephone set, relays 205, 209, a listening key to include said set in circuit with the calling line and to energize relay 205, a circuit to `energize relay 209 closed when the tip of the plug is placed in engagement with the sleeve of the Jack, a circuit includingy said set andan armature and front contact of relay 205, said circuit being closed by the operation of relay 209 to produce a single click in said set, a source of interrupted current, and a shunt about said relay 205 closed when the calling and called lines are the same, adapted todenergize relay 205, said relay at its back contact connecting said source yto said set to produce a tone therein.

L1. In a telephone exchange system, `the combination with calling and called telephone ylines including party lines, jacks wherein said lines terminate as called lines, a connecting circuit includinga calling plug, means for associating calling lines with said connecting circuit, an operators telephone set, a key for associating the same with said connecting' circuit, of a relay 205 associated with said connecting circuit energized when said key is operated, a shunt about said relay -to denergize the same when the calling plug is placed in contact with a called sleeve Vwhich is a multiple of the calling sleeve,

a relay 209 connected to the tip of the calling plug and energized when said tip -is placed in engagement with the sleeve of a busy line to close a circuit including a front contact of said relay 205 and said set to produce a signal of onecharacter in said set, or a circuit including a back contact of said relay 205 and said set to produce a signal of another character, dependent upon the character of the call.

5. In a telephone exchange system, the combination With telephone lines, finders to which said lines are multipled, driving circuits therefor, means including an extended starter Wire for associating said lines with an idle finder, means actuated upon the initiation of a call to close the driving circuit of the finder apportioned to the calling group it idle, and also to close the driving circuit ci' the next idle finder, and means actuated in case said first named finder is idle to prevent the closure of such last named circuit.

6. 1n a telephone exchange system, the combination with telephone lines, finders to which said lines are multipled, driving circuits therefor, means for associating said lines with an idle nder including an extended starter Wire, a relay 102 energized upon the initiation of a call to cause the closure ot the driving circuit of the finder apportioned to the calling group if idle, and also the driving circuit of the neXt idle linder, and a relay 131 associated with relay 102 energized only in case said rst named nder 1s idle to openv said last named circuit.

7. In telephone exchange system, the combination with telephone lines having multiple calling and called test terminals, a connecting circuit, means for associating a calling line With said connecting circuit and changing the electrical condition of its test terminal, and an operators telephone set adapted to loe associated With said connect`V ing circuit, oi: a discriminating relay associated with said connecting circuit, a circuit adapted to energize the same, a key for closing said circuit, a. shunt about said relay todenergize the saine when the called line is tested it such line is a multiple of the calling line, a relay energized during such testing operation to closel a circuit including the front contact of said discriminating relay and said set to produce a signal of one character in said set, or a circuit including aback Contact of said discriminating relay and said set to produce a signal of another character, dependent upon the character of the call.

1n Witness whereof, l hereunto subscribe my name this 18th day of May A. D., 1916.

BERT Gr. DUNHAM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

